Electric Submersible Pumps (ESP) are widely used in the production of fluid from oil and gas wells. Traditional ESPs have a centrifugal pump coupled to an electric motor. The motor is typically protected from wellbore fluid ingress by a seal (also referred to as protector or equalizer). The seal section is located between the motor and the pump which serves to reduce any pressure difference between the wellbore fluid exterior of the motor and the lubricant on the interior of the motor.
The rotary pump in many ESPs includes a rotating shaft, impeller, and stationary diffuser. The impellers are coupled to the shaft and create lift as they rotate, driving wellbore fluid up the well. A standard induction type motor may include a single continuously wound stator, a single shaft, one or multiple induction type rotors mounted on the shaft, and rotor bearings to the centralize the shaft.
Various disclosed embodiments of the invention may have one or multiple advantages over standard ESP units. Some disclosed embodiments utilize a wider range of operating speeds, utilize an active cooling system to reduce motor temperature rise, reduce the amount of time required to assemble or install a unit, and/or improve the power efficiency of the ESP system.
Disclosed embodiments may also reduce the inventory required through the use of standardized components, reduce capital requirements, reduce personnel requirements, and/or decrease rig exposure to an open well bore during installation, thereby increasing safety.
Some of the disclosed embodiments incorporate high-speed downhole components including pumps, seals, gas separators, intakes, motors and/or downhole sensors.
Some embodiments comprise a permanent magnet synchronous motor with a control system for speed regulation. Some embodiments may additionally or alternative comprise a high-speed pump, seal section and/or gas separator connected and aligned along a common axis. In some embodiments, the motor may be of modular construction and/or have an active cooling system that increases heat removal from the system via lubricant circulation through a heat exchange module. In certain embodiments, a downhole sensor may be utilized to control the operation of the ESP in substantially real time.